This invention relates to a new antibiotic substance, which has been designated CP-61,405. Said new antibiotic substance was isolated from fermentations of a new microorganism of the genus Streptomyces. The new microorganism was obtained from a soil sample found in Dazaifu, Fukuoka Prefecture, Japan and it has been assigned the code number N478-13. Chemically, the new antibiotic substance of this invention is a new member of the so-called polyether class of antibiotics, and it can be compared with Antibiotic X-14885A (U.S. Pat. No. 4,352,934).